Q. How do I determine how big my power supply is?

A. You can determine the total output of a power supply by physically examining the power supply. All power supplies have a sticker on the power supply that gives all important specifications, including the total output of the power supply.
If you have a computer that is already assembled, you can determine how big the power supply is by opening the computer and examining the power supply.
Many power supply manufacturers also use the wattage of the power supply in the model number. For example, the model number APS-500S, which is an indication of a 500W PSU.
If you’re unable to find a sticker or any identification on the power supply from examining it while installed in the computer it’s possible that the identification may be on a side that is not visible. If this is the case you would need to remove the power supply before being able to identify it.